Compositions containing amorphous 1,2-polybutadiene and cis-1,4-polybutadiene

ABSTRACT

New compositions consisting of 40-75 percent by weight of amorphous 1,2-polybutadiene having a molecular weight above 50,000 and 25-60 % by weight of 1,4-cis polybutadiene having a molecular weight above 100,000 result in sulfur vulcanizates having a low brittle point, a high elasticity modulus, and a low rebound and which swell to a relatively low degree when immersed in benzene.

United States Patent 1 Lesage et al.

1 51 Apr, 3, 1973 [54] COMPOSITIONS CONTAINING AMORPHOUS 1,2-POLYBUTADIENE AND CIS-l,4-POLYBUTADIENE [75] Inventors: Jean Lesage, Le Vesinet; Francois e Dawans, Bougival, both of France [73] Assignee: Institut Francois du Petrole, des Carburants et Lubrifiants, Hauts de Seine, France 22 Filed: Oct. 8, 1970 21 Appl. No.: 79,285

[30] Foreign Application Priority Data Oct. 21, 1969 France ..6936148 [52] U.S. Cl ..'..260/33.6 AQ, 260/4l.5 R,

V 260/45.75 R, 260/459 R, 260/4595, 260/894 [51] Int. Cl. ..C08d 9/08 [58] Field of Search ..260/894 [56] I I References Cited I UNITED STATES PATENTS 3/1970 Nordsiek et 51. ..260/5 FOREIGN PATENTS OR APPLICATIONS 684,622 4/1964 Primary Examiner-Samuel H, Blech Assistant ExamirierJOhn Seibert Attorney-Millen, Raptes and White 57 ABSTRACT 4 Claims, No Drawings Safford et al ..260/45.S

Canada ..'...260/894 1 This invention relates to new compositions contain tadiene content by weight of 25 to 60 percent, and a 1,2-polybutadiene content by weight of 40 to 75 percent.

These new compositions may be obtained by any ing amorphous 1,2-polybutadiene of high molecular 5 conventional technique for admixing elastomers. For weight. example,zthe constituents may be admixed in a roll- These compositions consist essentially of mixtures, in mixer at any convenient temperature, for example 30 critical proportions, of amorphous l,2-polybutadiene to 80 C. of high molecular weight and another polymerized un- During this operation, conventional additives may be saturated hydrocarbon having elastomeric properties, incorporated into the mixture, for example antioxiessentially l,4-cis polybutadiene. 'dants, such .as phenyl- B -nap hthylaniine or tert butyl Amorphous 1,2-polybutadiene of high molecular paracresol, various charges, such as carbon black, weight is a known compound. It contains at least 90 hydrocarbon oils, vulcanization agents such, as sulfur, percent of l,2-units and has a crystallinity content of vulcanization accelerators, or again zinc oxide or stearless than 2 percent, as determined at 20 C, and an ic acid. average molecular weight of at least 50,000. The resulting product may .be vulcanized in a press These characteristics may be determined according under known conditions of temperature (about to the following methods: l30180 C, preferably 150 C) and pressure (for exthe microstructure (content of 1,2-units) by the ample l to 100 bars, preferably about 70 bars).

infra-red spectrometric method, for example according to Ciampelli et al., in La Chemica e lln- EXAMPLES dustria 41, lg59ipage ln order to show the properties of these composithe weight average moleeuiaf Weight by the light tions, there have been made variousmixtures of -l,2-

Scattering method polybuta'dien'e having a l,2-units content of 91 percent, the crystallinity Content at C by X'ray Spectrog a crystallinity content of less than 2 percent and an p for example according to the method average molecular weight of 400, 000, with l,4-cis described in the Belgian 549, 554 of polybutadiene having a 1,4 cis units content of 96 per- 1957 or the French M54938 (USP 2 905 cent and an average molecular weight of450,000. 5 Various vulcanization additives have been added These amorphous lvz'pelybutadlenes are practically thereto, while operating in an open mixer-at 50 C, as free of gel and are soluble in a number of usual solf n j Vents, for example benzene, toluene, chloroform or i To 30 kg of mixture, the following have been added: carbon sulfide. They have been described, as well as t their manufacture, for example in USP 3 451 987.'The Pheny| p vnaph,hy]amine 03 kg conventional vulcanization treatments may be applied Aromatic oil 4.5 kg thereto, such as those commonly applied to the hevea 3 2:; gums, for example vulcanization by means of sulfur or Condensation product of diphenylamine sulfur compounds, with various added charges. I with acetone kg However, vulcanizates obtained from amorphous 40 g i g :22 l,2-polybu tadiene such as hereinbefore defined, have N-cyclohexyl-2-benzothiazyl not been satisfactorily used in the tire industry, particu- Sulfenamide 03 larly in view of their'insufficient properties in the cold: I they have a a brittle point of about 20 C which is The resulting mixtures have been maintained at l50 much too high as compared with the maximal value of C and 70 bars for 30 minutes, so as to obtain vul- 45 C required by tire manufacturers. canizates. .The composition and the properties of these The main object of this invention is to provide new vulcanizates are given in the following table:

Vulcanizate number 1 2 3 4 5 6 7 g g l,4-cis polyhutad. (percent) v 25 30 40 Q 1,2-polybutad. (percent) 75 70 60 50 40 20 0 Modulus at 300%, kgJcmJ. 1.. 05 118 106 102' 9:; s4 82 Resistance to breaking, ktzJi-m. 124 132 130 133 131 120 131 Rebound (Schoh) (percent) 15.6 21.1 22.8 26.2 20.4 39.2 40.2 43.3 45,6 Hardness DIDC 62 (i2 63 (35 64- 65 4 65 G1 Brittle p0lnt, c 2-t 59 '12 x0 -sn -s0 s0 -s0 a0 34o :m 323 :ns :ns 321 an; an; 332

Swelling in benzene (percent by woight) From these results, it appears that: g

l. The brittle point is below -45 C forvulcanizates containing at least 20 percent of l,4-cis polybutadiene.

This sharp decrease could 'not be deduced from the values corresponding to the vulcanizates obtained from l,2-polybutadiene alone and l,4-cis polybutadiene alone. 2. The elasticity modulus at.300 percent is unexpectedly increased between 20 and 80 percent, particularly between 25 and 60 percent.

3. The swelling in benzene is substantially decreased in the same 25-60 percent range.

4. The rebound remains low in this concentration range.

Tires manufactured from these compositions have shown a better behavior on road.

The new compositions may be used with advantage for manufacturing damping rubber and driving belts.

What is claimed as this invention is:

1. A composition consisting essentially of a mixture of (a) a polybutadiene having a 1,2-units content of at least 90 percent, a crystallinity lower than 2 percent at 3. A composition as defined by claim further com- 7 prising an aromatic oil.

4. A sulfur-vulcanizate of the composition of claim 3. 

2. A sulfur-vulcanizate of the composition of claim
 1. 3. A composition as defined by claim 1 further comprising an aromatic oil.
 4. A sulfur-vulcanizate of the composition of claim
 3. 